The present invention relates to a photographic film and a method of reading a frame number of the photographic film, and more particularly to a photographic film with bar codes indicating frame numbers of the photographic film and a method of reading the bar codes of the photographic film.
A 135-type of roll film is attached with DX binary bar codes indicating the type of film, the speed of the film, or the like. The bar codes are latent images formed in a side margin of the film. Upon printing, the DX bar code is read with a bar code sensor or bar code reader to correct an exposure amount according to the film speed.
The roll film also is attached with main serial frame numbers indicated by decimal numbers and supplementary serial frame numbers indicated by decimal numbers and alphabetical letters arranged at regular intervals which are used to specify the respective frames upon printing. It is known to print a bar code indicating a frame number in addition to each serial frame number so as to read automatically the frame number for identifying a picture frame. The frame number bar code is used to locate automatically a frame in the exposure position for making an extra print of the frame and/or to print a frame number on the print.
Upon loading a roll film in a camera, withdrawing a film leader out of the film patrone reduces the exposures of the film. To make it possible to make as many exposures as assigned, the film is provided with an extra exposable part which is indicated by an identification sign or mark, such as a letter "E" as an extra frame number. For example, a roll film, having 12, 20, 24, or 36 frames, has an extra part or frame attached with an identification mark "E" after a frame number of "12A", "20A", "24A", or "36A", respectively.
In the roll film having an extra frame attached with frame number "E", the bar code reader sometimes erroneously reads the extra frame number "E" if the extra frame number "E" is scratched, has foreign articles, or fogged. As a result, distinguishing the last frame, such as a 12th, 20th, or 24th frame, from the extra frame "E" is difficult. However, because the longest roll film has 36 exposures, the last frame or 35th frame can be distinguished by storing data in the printer indicating that the extra frame "E" is after the 36th frame.
It is, therefore, an object of the present invention to provide a photographic film having frame number bar codes in which the last frame may be distinguished even when the frame number bar code for the last frame is read incorrectly. It is a further object to provide a method of reading frame number bar codes of the film.